Classification, Heredity and Evolution

What You Need to Know

You need to know how population size is determined by births, deaths, immigration, emigration and limiting factors.

You need to be able to use data about population dynamics, abiotic factors, and biotic factors to explain a change in carrying capacity and population size in an ecosystem.

You need to know that different types of organisms exist within aquatic systems due to chemistry, geography, light, depth, salinity, and/or temperature.

You need to know the potential changes in an ecosystem resulting from seasonal variations, climate changes and/or succession.

You need to know the positive or negative consequences that result from a reduction in biodiversity.

Example One

Mullet are local estuarine fish that move in schools and feed on plankton and plant matter. Natural predators of the mullet include spotted sea trout, sharks, pelicans and dolphins. The graph below shows how the number of mullet in an area has changed over time.

Based on the data, one student concludes that a new predator was introduced into the area during this time period. Which of the following is a likely alternate explanation for the change in the mullet population?

Example Eight

The common brushtail possum is a marsupial native to Australia. This possum was introduced to New Zealand where it had no natural predators and had an abundant food supply. Which of these likely occurred a few years after the introduction of this possum to New Zealand?

Example Nine

The number of pythons found throughout Everglades National Park has increased in recent years. These huge snakes are not native to Florida and are believed to have been released into the wild by pet owners. Wildlife biologists have initiated attempts to capture and remove these pythons. Which statement best explains the biologists' reasons for removing these pythons from the Everglades?

A. The pythons could upset the territorial boundaries of native organisms.

B. The pythons could adapt to overcome diseases common to native snakes.

C. The pythons could prey on native organisms and cause native population to decline.

D. The pythons could begin to interbreed with native snakes and produce a more successful species.